Mice may permanently shed a fear of felines when infected with a parasite. The effects linger long after the parasites disappear, a study shows.

The protozoan parasite Toxoplasma gondii can infect most mammals, including humans (SN: 1/26/13, p. 24). But the parasite can reproduce only in the feline gut, so cats need to eat animals infected with T. gondii to keep the parasite generations going.

Perhaps increasing the likelihood that it will wind up in the belly of a cat, the parasite makes infec...